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  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 372 (1994), S. 537-540 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The Bermuda Atlantic Time-series Study (BATS; part of the US Joint Global Ocean Flux Study (JGOFS)) has sampled the Sargasso Sea (31° 50' N, 64° 10' W) biweekly to monthly since October 1988. The programme includes measurements of most components of the carbon cycle using ...
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  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 353 (1991), S. 420-423 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The activity of 234Th (half-life 24.1 days) in the oceans is primarily controlled by production from its soluble parent, 238U (half-life 4.5 x 109 years), and losses through radioactive decay plus sorptive removal on sinking particles. A typical 234Th profile in the open ocean shows relatively low ...
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 359 (1992), S. 221-223 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The boundary between the dissolved and particulate phase in the oceans has traditionally been defined operationally using filters of 0.2-1 jjim pore size. Owing to their small size, of order 1 nm to 1 jjim (ref. 17), and flexible nature1, colloids can pass through such filters and thereby be ...
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  • 4
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillan Magazines Ltd.
    Nature 398 (1999), S. 502-505 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Phosphorus is an essential nutrient in pelagic marine ecosystems. Phosphorus cycling in the upper ocean is, however, poorly understood, and few studies have directly investigated the biological utilization of this essential element. Here, we have determined in situ phosphorus-turnover rates in ...
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  • 5
    Publication Date: 2017-12-21
    Description: Author Posting. © The Authors, 2006. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Marine Chemistry 100 (2006): 213-233, doi:10.1016/j.marchem.2005.10.013.
    Description: Thorium-234 is increasingly used as a tracer of ocean particle flux, primarily as a means to estimate particulate organic carbon export from the surface ocean. This requires determination of both the 234Th activity distribution (in order to calculate 234Th fluxes) and an estimate of the C/234Th ratio on sinking particles, to empirically derive C fluxes. In reviewing C/234Th variability, results obtained using a single sampling method show the most predictable behavior. For example, in most studies that employ in situ pumps to collect size fractionated particles, C/234Th either increases or is relatively invariant with increasing particle size (size classes 〉1 to 100’s μm). Observations also suggest that C/234Th decreases with depth and can vary significantly between regions (highest in blooms of large diatoms and highly productive coastal settings). Comparisons of C fluxes derived from 234Th show good agreement with independent estimates of C flux, including mass balances of C and nutrients over appropriate space and time scales (within factors of 2-3). We recommend sampling for C/234Th from a standard depth of 100 m, or at least one depth below the mixed layer using either large volume size fractionated filtration to capture the rarer large particles, or a sediment trap or other device to collect sinking particles. We also recommend collection of multiple 234Th profiles and C/234Th samples during the course of longer observation periods to better sample temporal variations in both 234Th flux and the characteristic of sinking particles. We are encouraged by new technologies which are optimized to more reliably sample truly settling particles, and expect the utility of this tracer to increase, not just for upper ocean C fluxes but for other elements and processes deeper in the water column.
    Description: Individuals and science efforts discussed herein were supported by many national science programs, including the U.S. National Science Foundation and U.S. Department of Energy. S.F. and J.C.M. acknowledge the support provided to the International Atomic Energy Agency (IAEA) Marine Environment Laboratory by the Government of the Principality of Monaco. T.T. acknowledges support from the Australian Antarctic Science Program. K.B. was supported in part by a WHOI Ocean Life Institute Fellowship.
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
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  • 6
    Publication Date: 2017-01-04
    Description: Author Posting. © Elsevier B.V., 2007. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part I: Oceanographic Research Papers 55 (2008): 108-127, doi:10.1016/j.dsr.2007.10.006.
    Description: The sinking of particles that make up the biological pump is not vertical, but nearly horizontal. This means that the locations where the particles are formed may be distant from their collection in a sediment trap. This has led to the development of the concept of the statistical funnel to describe the spatial-temporal sampling characteristics of a sediment trap. Statistical funnels can be used to quantify the source region in the upper ocean where collected particles were created (source funnels) or the location of the collected particles during that deployment (collection funnels). Here, we characterize statistical funnels for neutrally-buoyant, surface-tethered and deep-ocean moored trap deployments conducted just north of Hawaii in the Pacific Ocean. Three-dimensional realizations of the synoptic velocity field, created using satellite altimeter and shipboard acoustic Doppler current profiler data, are used to advect sinking particles back to their source for sinking velocities of 50 to 200 m per day. Estimated source and collection funnel characteristics for the 5-day collections made by neutrally-buoyant and surfacetethered traps are similar with typical scales of several km to several 10’s of km. Deep moored traps have daily source funnel locations that can be many 100’s of km distant from the trap and have long-term containment radii that range from 140 to 340 km depending upon sinking rate. We assess the importance of particle source regions using satellite estimates of chlorophyll concentration as a surrogate for the spatial distribution of particle export. Our analysis points to the need to diagnose water-parcel trajectories and particle sinking rates in the interpretation of sinking particle fluxes from moored or freely-drifting sediment traps, especially for regions where there are significant horizontal gradients in the export flux.
    Description: We gratefully acknowledge the National Science Foundation’s Chemical and Biological Oceanography Programs (Grants OCE-0327318 and OCE-03-01139) and the Department of Energy’s Carbon Sequestration Program (Grant DE-FG02-03ER63697) for supporting our work on VERTIGO.
    Repository Name: Woods Hole Open Access Server
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  • 7
    Publication Date: 2017-01-05
    Description: Author Posting. © American Geophysical Union, 2005. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 110 (2005): C09S16, doi:10.1029/2004JC002601.
    Description: Comparison of eight iron experiments shows that maximum Chl a, the maximum DIC removal, and the overall DIC/Fe efficiency all scale inversely with depth of the wind mixed layer (WML) defining the light environment. Moreover, lateral patch dilution, sea surface irradiance, temperature, and grazing play additional roles. The Southern Ocean experiments were most influenced by very deep WMLs. In contrast, light conditions were most favorable during SEEDS and SERIES as well as during IronEx-2. The two extreme experiments, EisenEx and SEEDS, can be linked via EisenEx bottle incubations with shallower simulated WML depth. Large diatoms always benefit the most from Fe addition, where a remarkably small group of thriving diatom species is dominated by universal response of Pseudo-nitzschia spp. Significant response of these moderate (10–30 μm), medium (30–60 μm), and large (〉60 μm) diatoms is consistent with growth physiology determined for single species in natural seawater. The minimum level of “dissolved” Fe (filtrate 〈 0.2 μm) maintained during an experiment determines the dominant diatom size class. However, this is further complicated by continuous transfer of original truly dissolved reduced Fe(II) into the colloidal pool, which may constitute some 75% of the “dissolved” pool. Depth integration of carbon inventory changes partly compensates the adverse effects of a deep WML due to its greater integration depths, decreasing the differences in responses between the eight experiments. About half of depth-integrated overall primary productivity is reflected in a decrease of DIC. The overall C/Fe efficiency of DIC uptake is DIC/Fe ∼ 5600 for all eight experiments. The increase of particulate organic carbon is about a quarter of the primary production, suggesting food web losses for the other three quarters. Replenishment of DIC by air/sea exchange tends to be a minor few percent of primary CO2 fixation but will continue well after observations have stopped. Export of carbon into deeper waters is difficult to assess and is until now firmly proven and quite modest in only two experiments.
    Description: This research was supported by the European Union through programs CARUSO (1998– 2001), IRONAGES (1999 –2003), and COMET (2000–2003); the Netherlands- Bremen Oceanography program NEBROC-1; and the Netherlands Organization for Research NWO through the Netherlands Antarctic Program project FePath. Both the U.S. National Science Foundation and the U.S. Department of Energy provided significant support for the SOFeX program. M.R.L. acknowledges the U.S. National Science Foundation for support of IronEx and SOFeX projects and related studies (OCE-9912230, -9911765, and -0322074).
    Keywords: Iron ; Fertilization ; Phytoplankton
    Repository Name: Woods Hole Open Access Server
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  • 8
    Publication Date: 2017-01-05
    Description: Author Posting. © The Author(s), 2011. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Marine Chemistry 126 (2011): 108-113, doi:10.1016/j.marchem.2011.04.004.
    Description: Photosynthesis by marine phytoplankton requires bioavailable forms of several trace elements that are found in extremely low concentrations in the open ocean. We have compared the concentration, lability and size distribution (〈 1 nm and 〈 10 nm) of a suite of trace elements that are thought to be limiting to primary productivity as well as a toxic element (Pb) in two High Nutrient Low Chlorophyll (HNLC) regions using a new dynamic speciation technique, Diffusive Gradients in Thin-film (DGT). The labile species trapped within the DGT probes have a size that is smaller or similar than the pore size of algal cell walls and thus present a proxy for bioavailable species. Total Dissolvable trace element concentrations (TD concentration) varied between 0.05 nM (Co) and 4.0 nM (Ni) at K2 (Northwest Pacific Ocean) and between 0.026 nM (Co) and 4.7 nM (Ni) in the Southern Ocean. The smallest size fractionated labile concentrations (〈 1 nm) observed at Southern Ocean sampling stations ranged between 0.002 nM (Co) and 2.1 nM (Ni). Moreover, large differences in bioavailable fractions (ratio of labile to TD concentration) were observed between the trace elements. In the Northwest Pacific Ocean Fe, Cu and Mn had lower labile fractions (between 10 and 44%) than Co, Cd, Ni and Pb (between 80 and 100%). In the Southern Ocean a similar trend was observed, and in addition: (1) Co, Cd, Ni and Pb have lower labile fractions in the Southern Ocean than in the Northwest Pacific and (2) the ratios of 〈1nm to dissolvable element concentrations at some Southern Ocean stations were very low and varied between 4 and16 %.
    Description: This research was supported by Federal Science Policy Office, Brussels, through contracts EV/03/7A, SD/CA/03A, the Research Foundation Flanders through grant G.0021.04 and Vrije Universiteit Brussel via grant GOA 22, as well as for K2, the VERTIGO program funding primarily by the US National Science Foundation programs in Chemical and Biological Oceanography
    Keywords: Trace elements ; Speciation ; Bioavailability ; Pacific Ocean ; Southern Ocean
    Repository Name: Woods Hole Open Access Server
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  • 9
    Publication Date: 2016-09-22
    Description: Dataset: Niskin bottle samples
    Description: This Establishing Radionuclide Levels in the Atlantic and Pacific Oceans Originating from the Fukushima Daiichi Nuclear Power Facility (Fukushima Radionuclide Levels) Niskin bottle samples dataset includes the following data: calibrated CTD measurements of salinity and oxygen and Niskin bottle water samples. For a complete list of measurements, refer to the supplemental document 'Field_names.pdf'. A full dataset description is included in the supplemental file 'Dataset_description.pdf'.
    Description: Gordon and Betty Moore Foundation Marine Microbiology Initiative (MooreMarMicro), NSF Division of Ocean Sciences (NSF OCE) OCE-1136693
    Keywords: Fukushima Radionuclide Levels ; Niskin bottle data ; CTD Sea-Bird SBE 911plus data
    Repository Name: Woods Hole Open Access Server
    Type: Dataset
    Format: text/csv
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  • 10
    Publication Date: 2017-01-04
    Description: Author Posting. © American Geophysical Union, 2013. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 40 (2013): 1557–1561, doi:10.1002/grl.50219.
    Description: In the past two decades, a number of studies have been carried out in the Southern Ocean to look at export production using drifting sediment traps and thorium-234 based measurements, which allows us to reexamine the validity of using the existing relationships between production, export efficiency, and temperature to derive satellite-based carbon export estimates in this region. Comparisons of in situ export rates with modeled rates indicate a two to fourfold overestimation of export production by existing models. Comprehensive analysis of in situ data indicates two major reasons for this difference: (i) in situ data indicate a trend of decreasing export efficiency with increasing production which is contrary to existing export models and (ii) the export efficiencies appear to be less sensitive to temperature in this region compared to the global estimates used in the existing models. The most important implication of these observations is that the simplest models of export, which predict increase in carbon flux with increasing surface productivity, may require additional parameters, different weighing of existing parameters, or separate algorithms for different oceanic regimes.
    Description: This work was supported by NASA award number NNX08AB48G.
    Description: 2013-10-23
    Keywords: Biological pump ; Southern Ocean ; Carbon export
    Repository Name: Woods Hole Open Access Server
    Type: Article
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